Unravelling the Mysteries of Training Frequency for Hypertrophy

As discussed in my article on manipulating intensity, volume and frequency for muscle gain, training frequency is one of the most important variables to consider for hypertrophy. In this instance, training frequency relates to how often a given muscle is trained rather than how often you train in the gym.

Science gives us some useful insights into this topic. It indicates that splitting the same training volume into more frequent training sessions is better for hypertrophy. This is likely due to a more optimal distribution of training stimuli across the week. In fact, several physiological markers show superior results with training programs which match overall volume through high-frequency approaches which use less volume per session.

The evidence clearly illustrates that training muscles twice per week is superior to training a muscle once per week. Other research indicates that training frequencies higher than twice per week are optimal for hypertrophy. Most traditional bodybuilding programs have you training a muscle directly only once per week (e.g., the bro split) or twice per week (e.g., upper/lower or push/pull/legs). In my opinion, these splits limit your muscle building ability.

Body Part Splits - Why?

Because they evenly distribute training frequency and cap a muscle’s frequency at a maximum of twice per week. It is my contention that for maximal growth some muscles require a higher frequency than this. Most traditional splits, therefore, fail to maximize your growth in these muscles for this very reason.

The fundamental flaw in the symmetrical training splits out there is that they lack a consideration for the differences between muscle groups. Different muscles respond best to different intensity, volume and frequency prescriptions. Primary amongst this is how quickly they recover from training and, therefore, how soon they are ready to be trained again. Frequency of training shouldn’t be considered a blanket, body-wide issue, but a muscle-specific one.

To maximize your results, you need to optimize your training frequency for each and every muscle. The problem is that people like easily packaged symmetrical training splits which neatly fit within the seven-day week. I completely understand this. From a logistical standpoint, it is far simpler. Convenience is nice. It rarely results in outstanding results though.

The question is, do you want simple and convenient or do you want exceptional results?

If you answered simple it doesn’t make you a bad person. You can still get good results. They just won’t be quite as good as they could be.

For those that answered exceptional you will need to invest just a little brain power and creative thinking to build the perfect training frequency for you and every one of your muscles.

While science hasn’t identified muscle-specific frequency guidelines it does provide a large number of clues we can use to start piecing the optimal frequency puzzle together. A range of training a muscle 2-4 times per week has been identified as effective for hypertrophy. Pinpointing where on this spectrum each of your muscles lies means you can bespoke your training at a whole new level. Not just to you, but to each and every one of your muscles. That creates the possibility of you growing at the fastest possible rate for every muscle group. Not as is commonly the case having some muscles lagging behind while others take center stage.

SRA – The Key Determinant of Training Frequency

Stimulus, Recover, Adaptation (SRA) describes the entire sequence of events which occur during, after, and before each training session. It is a sports science adaptation of Hans Selye’s General Adaptation Syndrome (GAS). Training is the stressor/stimulus. Following training, the body has to recover back up to baseline. Then finally, adaptation can occur.

Each muscle has a different SRA curve. This is a fancy way of saying some muscles recover and adapt quicker than others after training. On that basis, your training frequency for each body part should reflect a muscle’s specific SRA timeframe. Your goal, as Fred Hatfield described it is to, “train each muscle when it is ready to be trained – never sooner and never later.” In sports science geek terminology that means you should train a muscle at the peak of its adaptation curve.

SRA curves for strength are different to power SRA curves, and skill SRA curves are different again. It should come as no surprise then, that hypertrophy SRA curves are also unique from other training qualities. The length of the hypertrophy SRA curve varies due to numerous factors. Your strength, training history, and level of muscle mass all play a role. Furthermore, the size of a muscle, it’s function, anatomy, fiber type ratio, structure and its propensity for muscle damage all contribute to its SRA curve.

While establishing a muscle’s hypertrophy SRA cycle is multi-factorial it is possible to narrow it down to roughly 24-72hrs for practically every muscle in the body. Although this range is relatively narrow it is still wise to try and fine tune your training to each muscle's exact SRA timeline. Think of it this way, training a muscle every 72 hours when it could tolerate every 24 hours will massively limit your rate of progress. Likewise hitting a muscle every day which requires 72 hours of recovery is a fast track to injury and overtraining.

To bring this point home ask yourself “how often could I train my abs and recover?” Then ask, “could I train my hamstrings hard this often?” I’m guessing the answer to the former is every day (or damn near) and the latter is, about every 4th day, or twice per week. Hopefully, this illustrates why following a symmetrical split is sub-optimal.

How to determine a muscle’s SRA

If you can identify a given muscle’s SRA then you can plan your training frequency around it for the best possible results.

To establish this, you first must consider the following overall factors:

Your training age/history/experience

Your strength levels

Your size and level of muscularity

Over your training career, you will become bigger and stronger. With this comes the ability to handle heavier loads. To overload yourself, you will require higher training volumes too. This all adds up to an increased ability to cause homeostatic disruption at every training session. With a higher stimulus comes a longer recovery period. As such, more experienced lifters will very often have longer SRA curves and, therefore, require a lower training frequency per body part.

Once your global or systemic factors have been considered it is then important to drill down into more detail on muscle-specific factors. These include:

The Fiber Type Ratio of a Muscle

A Muscle’s Size

A Given Muscle’s Anatomy

Lift/Exercise Specific Differences

Fiber type – Different muscle groups have different roles within the body. These diverse functional characteristics are the key contributing factor to why different have varying fiber type ratios. Some muscles are predominantly slow-twitch in fiber composition while others are fast twitch dominant.

Fast twitch fibers are much more powerful, have higher force production, but fatigue more quickly. They also take longer to recover. Slow twitch muscle fibers, however, tend to recover more quickly, both within a session and from session to session. Consequently, training slow twitch muscle more often is a wise decision.

The classification of muscle fiber type ratios is not an exact science as there is a great deal of inter-individual variability. With that said the literature does provide the following guidelines:

If you have a higher predominance of slower-twitch muscle fibers then you can most likely tolerate and benefit from higher frequency training. On the other hand, if you have above average numbers of fast twitch fibers then you will probably benefit from using lower rep ranges and lower frequencies of training.

Bigger Muscles Take Longer to Recover

Just like you can cause more disruption the bigger and stronger you get; larger and stronger muscles cause more disruption than smaller ones. Training your quads causes significantly more disruption and requires far more recovery than training biceps. The larger muscles of the body can produce more force. When training them you use heavier weights. Also, they obviously take up a larger surface area and comprise a greater amount of tissue. This tissue must be repaired and re-modelled before it can effectively be trained again. Obviously, this takes longer for larger muscles.

Size Is Not the Only Consideration to a Muscles Training Frequency

A muscle’s architecture must be considered. Muscle architecture varies from muscle to muscle and can influence force production, ability to stretch under load, take on muscle damage and cause homeostatic disruption. This needs to be considered when planning training frequency.

A primary example of how this impacts training frequency is the chest. It rarely benefits from being trained more than twice per week because of the fast twitch fibers, it’s ability to stretch under load and high degrees of muscle damage created when training it. Even though it is a relatively small muscle it’s ideal training frequency tends to be on the lower end of the scale. Meanwhile a larger muscle like the latissimus dorsi tends to benefit from higher training frequencies because it’s fibre type and architecture allow for this.

Exercise Frequency for Hypertrophy

Analysing training frequency by examining a muscle’s specific characteristics is an excellent foundation to base your training frequency decisions on. A muscle’s fiber ratio, size, anatomy and architecture tells most of the story, but not the whole story. The exercises you use in your training significantly impacts upon your training frequency.

The factors to consider when differentiating between exercises include, the quantity of muscle mass involved, the amount of force generated, movement complexity, nervous system activation, degree of stretch on working muscles, and the level of muscle damage created.

A practical tip is that compound barbell movements tend to be the hardest to recover from, then dumbbells, then cables or fixed machines. Isolation exercises also tend to be easier to recover from than multi-joint movements. So, at one end of the spectrum for chest is the barbell bench press and at the other is machine flyes.

When planning your training you must make a trade-off between choosing between the most effective exercises (generally multi-joint free weight exercises) and the super high frequencies possible with machine based isolation exercises. It doesn’t take a rocket scientist to work out that most of the time you’re best served training less frequently with the most effective exercises. I suggest you limit your training frequency to what you can tolerate while building the foundation of your training around the big lifts.

Another consideration is the amount of muscle damage caused by an exercise. Lifts which create high levels of stretch under load tend to cause very high levels of muscle damage. Some prime examples are Romanian deadlifts, good mornings, dips, paused bench presses, cambered bar presses, and sissy squats. Because of the muscle damage caused doing these recovery times are slightly extended.

When it comes to programming this is important to consider. Taking the hamstrings as an example, they respond very well to be trained twice a week. Now, say you structure your week to train hamstrings on a Monday and Thursday. It is probably best to do the RDLs and good mornings on a Thursday because these lifts take longer to recover from. Meanwhile making the bulk of your hamstring training on the Monday from leg curls is wise. After your Monday session, you have a quicker recovery time. This is useful as you are training the hamstrings again 72hours later. Then after the higher muscle damage caused on Thursday by RDLs and/or good mornings, you get 96hours recovery before hitting hamstrings the following Monday.

Range of motion (ROM) is also a consideration when it comes to exercise specific SRA curves. Movements with a greater ROM cause greater systemic fatigue as they have a higher workload. Work in physics is defined as: Force x Distance

Deficit deadlifts create more fatigue than pulling from blocks and bench presses require more work per rep than floor presses.

One final point to consider: It is worth noting that frequency shouldn’t be set in stone. Like other training variables, you will see the best results by manipulating it over time to optimize your training. For example, using moderate frequencies (1-3x per week) as the default setting for your program, with periods of more frequent training (i.e. 3-6x) used sparingly to achieve functional overreaching, to target a lagging body part or to bust through plateaus is a very effective training strategy.

Some General Guidelines

With all the above factors taken into consideration, it is possible to give some general guidelines for muscle-specific training frequencies.

4 days per week

Biceps, rear & lateral delts and calves

3 days per week

Back and triceps

2 days per week

Quads, hamstrings, chest and anterior delts

With this info, a training split like this would deliver an optimal training frequency for most; obviously, you could achieve the above by training 6 or 7 days per week.

Don’t have time to train every day? You could tag some additional work for the higher frequency muscles onto a standard upper/lower split like this and keep total training days to 4 per week:

Monday

Upper + Calves

Tuesday

Lower + Biceps, rear & lateral deltoids

Wednesday

Off

Thursday

Upper + Calves

Friday

Off

Saturday

Legs + lats, arms, dear & lateral deltoids

Sunday

Off

With the ‘tag’ on sets, volume doesn’t need to be too high. 2-3 sets per muscle group will get the job done and provide a sufficient stimulus while allowing you to hit the frequency guidelines above.

If you currently use a typical bro split, hitting each muscle once per week don’t jump straight to training back three times a week and smashing biceps, shoulders, and calves four times. Instead, gradually and incrementally increase your training frequency. Push biceps, rear and lateral delts up to twice per week. If that goes ok add calves and back. Once you have adapted to that continue to add sessions for other muscle groups until everything is being trained twice per week. Once that is done you can begin to increase the frequency of biceps, rear and lateral delts and calves again. Assuming all goes well repeat the process.

In several months, you will have intelligently increased your training frequency. Progressively overloaded your body and be set to benefit from an optimal training frequency. Throughout this process meticulously track your response. Identify patterns and see how different frequencies affect your progress. Can some muscles tolerate more frequency than others? In time, you will begin to identify your optimal training frequency for each body part. Once you arrive at these muscle-specific recovery rates you are then in a position to structure your program around them.